An automatic rifle (AR) is fed by a magazine so that the AR can fire repeatedly, for as long as the trigger is held down or until the magazine is exhausted. The magazine stores ammunition for the AR and feeds the ammunition into the AR. In some cases, the magazine is detachable or otherwise removable so that it can be attached and then removed and in some cases the magazine is integral with the AR. The magazine is responsible for positioning the cartridges appropriately with respect to the chamber of the rifle so that they can be loaded directly into the chamber by action of the firearm.